Die structure



W. J. SCHULTZ DIE STRUCTURE Aug. 15, 1933.

Filed Jan. 27, 1932 M... WL@ 1%.? am;

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Patented Aug. 1,5, 1933 UNITED STATES PATENT OFFICE 'DIE STRUCTURE William J. Schultz, Glassport, Pa., assignor'to Firth-Sterling Steel Company, a .Corporation of Pennsylvania This invention relates to a machine part formed of composite metals, and, while the principles involved will nd wide application in various fields, I will describe the invention as it is embodied in a wire or tube drawing die.

In my ,co-pending application, Serial No. 589,169 led January 27th, 1932, I have described an integral orificed die-block of cemented metallic carbide autogenously welded in a supporting casing or carrier of ferrous metal. Due to the hardness and durability of the carbide block, the die has many times the working life of any metallic dies employed heretofore. As disclosed in the above-noted application for patent, the oriiiced block is formed of what is known as cemented carbide of some of the more refractory metals, such as tungstenpr tantalum. The carrier for the block is preferably formed of a modified cast iron, such as the metal commercially known as Meehonite, which is the product of the methods described in United States Letters Patent No. 1,499,068, N0. 1,683,086,

No. 1,683,087, and No. 1,731,346.

Due to the cost of manufacture of cemented metallic carbides it is essential that a minimum of such material shall be used in a given structure. Accordingly, in a drawing die having a large bore, say a bore of three fourths of an inch in diameter or larger, it becomes a problem to provide a carbide block die without encountering prohibitive costs. dies having bores of a diameter of two inches or more, it becomes increasingly difcult to form an integral carbide die block.

The principal object of this invention is to provide large-sized dies, or other machine tools and parts, having an effective drawing-block of cemented carbide. Economy in the manufacture and efficiency of the nished product are also things in mind.

In Fig. I of the accompanying drawing there is shown in central vertical section a mold for the manufacture of a die embodying the invention. The carbide drawing-block of the die is r made up of a plurality of sections, one section fitting with another to complete the whole; and

in Fig. II one section of the block is shownA in perspective. Fig. III of the drawing is a central vertical section of a completed die. And Fig. IV is a View inside elevation, illustrating a modification in the means for holding the sections of the block in assembled annular relation preparatory to the casting of its supporting carrier.

I have discovered how, with advantageous re- Furthermore, in

sults, the cemented carbide drawing-block can be built of aplurality of complementary sections Which in assembly form a slightly tapering tube C. And preferably each section 1 is fashioned in general helical form from end to end for a purpose to be described presently. Means are provided for securing the sections in their assembled position while the supporting casing or carrier is cast and welded upon them. Such means comprise two shouldered rings 2, 2 (Fig. I) fitted over theupper and lower peripheral corners of the assembled sections, and several clamping rods or ties 3 are adjusted to hold the rings securely.

-A mold is provided for casting the supporting carrier around the sectional Yannular block C. In this case the mold is composed of baked sand, and comprises a stool 4, body 5 and top 6. A block-supporting stem 'l of baked sand is positioned centrally in the mold; it is suitably formed at its base to seat in socket 8 of the stool 4, and it is laterally supported adjacent its top by the cover 6. To enhance the sturdiness of the structure the stem may, in accordance with known foundry practice, be pasted in position in socket 8. A tapering shoulder 9 is provided on stem '7 to receive and to position the sectional annular block C, and foundry paste is also used with good effect in securing the block C upon the supporting stem 7.

Preferably the molten modified cast iron as disclosed in my above noted application and in the above-enumerated patents, is teemed into the mold gate 10, until the mold cavity is sub-K stantially lled. The rings 2 and desirably the ties 3 are all formed of the modified cast iron substantially identical with the metal teemed into the mold. The rings and ties are first thoroughly cleansed, so that, when the relatively large body of molten metal fills the mold,

the rings and ties 2, 3 are melted or fused and become integral with the cast carrier body. During the operation of forming the composite structure, the outer por-tions or surfaces'of the sectional tungsten carbide core become absorbed or dissolved in the molten metal, decrementally or in gradually decreasing quantities outwardly from the ultimate inter-face between the two metals. 'Ihus the cross-sectional areas immediately surrounding the undissolved carbide block will partake to some extent of the physical properties of the block itself, and areas further away will'partake of these properties to a lesser degree. It will be seen, therefore, that there is a gradation of physical properties away from the unaffected carbide block, through the immediately adjacent portions of the casing or carrier and outwardly, thus assuring the best possible bonding between the carrier and the carbide block, and overcoming any tendency of the block to be cracked or broken under the severe conditions of service.

It has been found that the body of such a composite die may, advantageously, include a passage for circulation of cooling fluid, such as water, and to this end I include in the mold an annular core member 11,*having attached thereto a pair of downwardly projecting legs 12, to form in the completed casting inlet' and outlet ports for the annular chamber formed by the core 11. The legs 12 of the core are pasted lin sockets 14 in the stool 4 of the mold, thus insuring that the corell will be rigidly secured against displacement during casting. In practice I prefer to provide gas vents 15 within the core 11 and legs 12, and the vents communicate with the atmosphere by way of passages 16 provided in stool 4. Additional gas vents 21 are provided in the top of the mold.

After the solidified casting has been removed from the mold, the core members 7, 11, and 12 are broken up in the usual manner and cleaned out of the casting. The casting is indicated in dotted lines in Fig. III, and the completed die is indicated in vertical section in full lines, illustrating approximately how the casting is machined down to provide the completed die. The inlet and outlet openings formed by the core legs 12 are threaded, and water pipes 20 are secured therein, as shown, affording connections for the circulation of cooling fluid within the chamber 17 of the die.

The openings 18 and 19 leading to and from the carbide block C are machined to desired shape, while the bore of the block itself is nally dressed and sized by means of a rotating tool supplied with a mixture of oil and diamond dust.

It is important to note that the sections 1 of which the annular carbide block is composed are made in helical form in thel direction of the axis of the die, and their curvature is such that the one end a of the parting line between one pair of sections overlaps the end b of the next parting line. That is to say, in the illustrated structure the point a lies opposite b with respect to a line d extending through the block wall parallel to its axis. This overlapping of the sections is of advantage in that any tendency of the edges of the sections to scratch.a rod or pipe moving in a linear direction through the die is eliminated. Additionally, it may be mentioned that I have found that any small crevices Iwhich may ultimately remain or be formed between the several sections of the annular block C provide regions within which small stores of lubricant may lie, and accordingly the lubrication of the Work moving through the die is greatly improved.

I show in Fig. IV a modified device for securing the block sections is assembled position, preparatory to casting the supporting carrier. A templet 50 is adapted to receivel the loosly assembled sections' 1 and to stay them in their desired relative position while a keeper ring 51 is driven over the downwardly tapering surface of the assembly C; the keeper ring tightly binds the sections in their desired relation, and the assembled sections and keeper ring may be fitted upon core 7 within the mold. The ring 51 may be formed of the modified cast iron, and, as explained in the case of rings 2, the ring 51 is absorbed or fused with the supporting carrier cast around the annular block. 'Ihe structure last described is of advantage in that it leaves the peripheral corners c of the assembled block C unobstructed to receive the cast metal.

It will be understood that 4the annular die block need not necessarily be of circular crosssectional form. For example, in drawing articles having angular or irregular shapes, the inner faces of the sections 1 of the die block, instead of being generally segmental in form, may be of the shape suitable for the particular operation.

I claim as my invention:

l. A machine part comprising an annular metallic carbide block formed of laterally contacting sections, and a supporting body of modied cast iron cast and autogenously welded upon and around the outer surface of the block.

2. A drawing die comprising an annular metallic carbide block formed of complementary sections, and a' supporting body of modiied cast iron cast and autogenously welded upon-and .around the outer surface of the block.

3. A drawing die comprising an annular metallic carbide block formed of sections having helically shaped contacting lateral faces, and a supporting body of modified cast iron cast and autogenously welded upon and around the outer surface of the block.

WILLIAM J. SCHULTZ. 

